The number of cerebrospinal axons regenerated into the caudal spinal cord increases in time after the lesion.

<p>(A–E) Retrogradely labeled neurons in RT (A–E), MaON (F–J), and NMLF (K–O) at two (A, F, K, respectively), four (B, G, L, respectively), six (C, H, M, respectively), and eight (D, I, N, respectively) weeks post-lesion and in unlesioned zebrafish (E, J, O, respectively). Boxplot diagrams demonstrating the median number (and confidence interval of median) of FE-labeled neurons in zebrafish at two, four, six, and eight weeks post-lesion and in unlesioned zebrafish in the whole brain (P), RT (Q), MaON (R), and NMLF (S). Asterisks indicate significant differences between groups (Kruskal-Wallis test, followed by Mann-Whitney U test with Bonferroni correction, p significant if ≤0.005). The numbers of total FE-positive neurons and FE-positive neurons in RT are significantly different between two weeks post-lesion and six weeks post-lesion. The number of FE-positive neurons in normal (unlesioned) group is not significantly different from six weeks post-lesion in the whole brain and in each of the examined nuclei. 2 wpl (n = 20); 4 wpl (n = 21); 6 wpl (n = 20); 8 wpl (n = 20), unlesioned (n = 19). Bar = 100 µm in A–O.